Power transmission



June 13, 1950 J. B. BLACK ETAL 2,511,039

POWER TRANSMISSION Filed March 5, 1948 5 Sheets-Sheet l Marg J. B. BLACK ETAL POWER TRANSMISSION June 13, 1950 5 Sheets-Sheet 2 Filed March 5, 1948 June 13, 1950 J. B. BI. ACK ETAL POWER TRANSMISSION 5 Sheets-Sheet 3 Filed March 5, 1948 June 13, 1950 J. 5. BLACK ETAL 2,511,039

POWER TRANSMISSION Filed llarch 5, 194B 5 Sheets-Sheet 5 N 03 (Mu i J'n/zrI/arv. fin 5. Fido/i. wilurtl 'jiluras.

NEW

\QQY W Patented June 13, 1950 UNITED STATES PATENT OFFICE POWER TRANSMISSION Application March 5, 1948, Serial No. 13,258

Claims. 1

Our invention relates to power transmissions and more particularly to an arrangement in which power may be hydraulically or directly transmitted to the load through a. selective, change speed gear mechanism, including a reverse gear.

Power transmission which embody hydraulic and direct drive features with the capacity to shift from one drive to the other are well known and desirable because the high starting torque developed in the hydraulic drive enables heavy loads to be rapidly and smoothly accelerated;

while the direct drive provides normal, full speed operation at maximum efllciency. However, it is well established that, in characteristic forms of such units, there is a period during the shift from hydraulic to direct drive, or vice versa, when the engine is not connected to the load and hence will accelerate rapidly which is objectionable. For example, in a typical unit wherein a hydraulic torque converter provides the hydraulic drive, the power source is selectively connected to the converter or directly to the driven shaft through friction clutches and in shifting from one drive to the other, the unavoidable time required to disengage one clutch and engage the other leaves an interval when the power source is unconnected to the load.

It is therefore one object of our invention to devise a power transmission arranged for selective hydraulic or direct drive through a change speed gear mechanism in which provision is made for effecting a full power shift between all forward speed gears in either direction under hydraulic or direct drive conditions so that the engine or other power source is at all times coupled to the load.

A further object is to provide a transmission having the above characteristics in which the power flow through any gear, including reverse gear, is not interrupted during the shift from hydraulic to direct drive, or from direct to hydraulic.

A further object is to devise a transmission as indicated in which the change speed mechanism employs constantly meshing spur gears whose power transmission is established by selectively controlled, hydraulically actuated clutches.

These and further objects of our invention will be set forth in the following specification, reference being had to the accompanying drawings, and the novel means by which said objects are effectuated will be definitely pointed out in the claims.

In the drawings:

Fig. 1 is a sectional elevation of the transmission with all clutches in disengaged position.

Fig. 2 is an enlarged, fragmentary, sectional elevation of the change speed mechanism as viewed in Fig. 1.

Fig. 3 is an enlarged, fragmentary section of the hydraulic torque converter which constitutes the fluid power transmitting part of the unit.

Fig. 4 is a section along the line 4-4 in Fig. 1 showing the idler gear for transmitting reverse drive to the output shaft.

Fig. 5 is a section along the line 5--5 in Fig. 1 showing the alternating relation of the bolts connecting the pistons for the low and reverse clutches, and the release springs for these clutches.

Fig. 6 is a sectional elevation of the control valve for regulating flow of actuating liquid to the several clutches, the parts of the valve occupying positions corresponding to the disengaged clutch positions shown in Fig. 2.

Fig. 7 is an end view of the multiple cam sleeve in the control valve looking in the direction of the arrow 1 in Fig. 6.

Fig. 8 is a diagrammatic, plan view of the control valve, shift lever guide as viewed in the direction of the arrow 8 in Fig. 6.

Fig. 9 is a schematic view of the hydraulic system for actuating the several clutches.

Referring to Figs, 1, 2 and 3, the numeral l0 designates a coupling flange that may be driven by an engine or other power source (not shown) and which is keyed to one end of a drivin or input shaft I l suitably journaled in the end walls I2 and I3 of a transmission housing [4.

A bladed pump l5 forming part of a hydraulic torque converter i6 is keyed to the shaft II adjacent the housing wall l2 and its outlet and inlet ends are respectively operably related to connected, bladed turbines i1 and i8 constituting first and second stages of the converter and which are keyed to one end of a driven sleeve I9 that extends towards the housing wall [3, is concentric with the shaft II and spaced therefrom for a purpose presently exp1ained. A bladed, reaction member 20 i located between the turbines ii and I8 and functions in the characteristic manner when power is transmitted through the converter. Between the converter [6 and the housing wall l2, the reaction member 20 is secured to a sleeve 2| that encircles and is journaled on the shaft H by a bearing 22, and a concentric sleeve 23 extends within the sleeve 2| and is appropriately secured against rotation to the housing 14. Interposed between the sleeves 2| and 23 is a freewheel or overrunnin clutch 24 of characteristic construction which is arranged to hold the reaction member station-f ary during power transmission through the converter and to permit its rotation with the pump within the housing I4 and by the end wall l3, andbetween these bearings is externally splined at able in the cylinder 49 and when moved towards the left frlctionally engages a plurality of annular 'plates constituting a low speed clutch 5|, herein- "after referred to as the low clutch, against an abutment ring 52 rigidly secured-to the driving ring 48. Alternate plates of the low clutch 5i have driven and sliding engagement with the ring 48 while the intervening plates have driving and sliding engagement with a sleeve 53 that is journaled on the main driven sleeve l9. The low clutch 5i is hydraulically engaged by means pres- 28 (see Figs. 2 and 5) for constant engagement with an internally splined, spur, carrier pinion 29, thus completing drive through the converter It to this point of the transmission.

For accomplishing direct drive from the engine to the same point, the driven shaft ll extends through a cover 30 (see Figs. I and 2) bolted to the housing wall I3 and is splined at 3| from the right end thereof for a convenient distance inwardly of the cover for driving engagement with a sleeve hub 32 forming part of a disk 33 which may be journaled on a bearing 34 carried by the right end of the driven sleeve l9. As shown in Fig. 1, the right extremity of the shaft I I may be exposed as at 35 for use as a power take-off driving auxiliary appliances.

Referring more particularly to Fig. 2, the left face of the disk 33 is annularly recessed to provide a shoulder on which is fitted a driving ring 36, a portion of whose inner surface forms with adjacent surfaces of the disk 33 an annular cylinder 31. An annular piston 38 is operable in the cylinder 31 and when-moved towards the left frictionally engages a plurality of annular plates constituting a direct drive clutch 39, hereinafter referred to as the direct clutch, against an abutment ring 40. Alternate plates of the direct clutch 39 have driven and sliding engagement with the ring 36 and the intervening plates have sliding and driving engagement with an annulus 4| that is interally splined at 42 to connect with the right end of the driven sleeve I9. The direct clutch 39 is engaged by hydraulic means and transmission of power therethrough, or through the converter I6, is a matter of selection, all as presently described. The piston 38 is moved to release position by a plurality of springs 43 spaced around the disk 33, only one spring being illustrated. One end of each spring 43 abuts the right side of the disk 33 and the opposite end bears against the washer 44 which engages the head of a cap screw 45 that extends slidably through the disk, is threaded in the piston 38, and provides driving connection between the disk 33 and piston 38.

From the foregoing, it will be apparent that power flow through the converter "5 or the direct clutch 39 is applied to the pinion 29 and the means whereby this flow is conditioned to produce definite forward and reverse, output speeds will now be described.

The left face of the pinion 29, as viewed in Fig.

2, is annularly counterbored to form an annular shoulder 46 and inwardly thereof an annular surface 41. Fitting on the shoulder 46 and extending normally away from the plane of the pinion 29 is a driving ring 48 and a part of the inner surface of this ring forms with the surface 41 and the radially included surface of the pinion an annular cylinder 49. An annular pistin 50 is slidently described and is moved to release position by parts associated with the reverse clutch and will be described in connection therewith.

A freewheel or overrunning clutch 54 is interposed between the sleeve 53 and a surrounding pinion which is journaled by a bearing 55 on the sleeve 53. The overrunning clutch 54 transmits power to the pinion 55 when power flows through the low clutch 5|, but runs free when the drive is through the high speed clutch, presently described, notwithstanding that the low clutch is engaged. The pinion 55 is in constant mesh with a gear 51 keyed to an output shaft 58 that is journaled in bearings 59 and 60 in the housing walls 21 and I3, respectively, and extends beyond the latter wall for connection to the load. Hence, when the low clutch 5| is en aged and the other speed clutches presently described are disengaged, the power source may drive through the converter IE or the direct clutch 39.

For the purpose of securing high speed drive, the pinion 29 is in constant mesh with a gear 6| freely journaled on the output shaft 58. The hub 62 of the gear 6! is splined at 63 for driving and relative sliding engagement with a plurality of annular plates constituting parts of a high speed clutch 64, hereinafter referred to as the high clutch, whose remaining plates are drivingly and slidably connected to a ring 65 bolted to the web of the gear 51. A portion of the inner surface of the ring 65 and a turned portion of the web of the gear 51 forms an annular cylinder 66 in which is slidable an annular piston 61. When moved towards the right, as viewed in Fig. 2 and as hereinafter described, the piston engages the plates of the high clutch 64 against an abutment ring 68 rigidly secured to the ring 66. In shifting from low speed to high speed, the characteristic method of operating this transmission leaves the low clutch 5i engaged when the high clutch 64 is engaged to provide a full power shift and the high clutch then takes the drive away from the low clutch by reason of the action of the overrunning clutch 54. The clutch 64 is bydraulically engaged by means presently described and the piston 61 is shifted to release position by a plurality of springs 69 spaced around the gear 51, only one being shown. One end of each spring 69 abuts the side of the web of the gear 51 which is opposite to the cylinder 66 and the other end of the spring bears against a washer 10 carried .by a cap screw 1| which slidably extends through the gear 51 and is threaded in the piston 61. The screws 1| additionally act as a driving connection between the gear 51 and the piston 61.

For reversing drive through the transmission, an annular cylinder 12 is provided on the pinion 29 in opposed and coaxial relation to the cylinder 49, and slidable in the former cylinder is a piston 13 which, when moved towards the right as viewed in Fig. 2 by hydraulic means presently described, engages a plurality of annular clutch plates constituting a reverse clutch 14. This engagement is effected against an abutment ring I8 rigidly secured to a driving ring I8 bolted to the web of the pinion 29, a portion of the inner surface of the ring I6 forming part of the cylinder I2. Alternate plates of the reverse clutch I4 have driven and sliding engagement with the ring I6 and the intervening plates have like engagement with the hub 11 of a gear I8 that is journaled on the driven sleeve I9 between the housing wall I3 and the 'pinion 29. The gear I8 is in constant mesh with an idler gear I9 (see Fig. 4) that is suitably carried by the housing and the gear I9 is in constant mesh with a gear 80 keyed to the output shaft 58. I

Release of the piston I3 is effected by a spring assembly interposed between the low clutch piston 50 and the pinion 29 and release of the latter piston is accomplished by a spring assembly interposed between the piston I3 and the same pinion. As indicated in Fig. 2, the pistons 50 and I3 are tied together for simultaneous movement by screws M which are slidable through the web of the pinion 29 and drivably connect the pistons thereto. Any desired number of these screws are spaced around the pinion 29, a characteristic arrangement being shown in Fig. 5

' and intervening between the screws are pockets 82 and 83 in the pistons 50 and I3, respectively. In each pocket 82 is mounted a spring assembly comprising a helical spring 84 whose ends respectively abut outer flanges provided on cupshaped washers 85 and these flanges constantly bear respectively against the end wall of the pocket and the adjacent side of the pinion 29. Extension of the spring 84 is limited by engaging inner flanges on the washers with spaced, retaining rings 86 mounted on a carrier 81. Springs 88 identical with the springs 84 are positioned in the pockets 83 and each spring 88 forms part of an assembly like that described for the springs 84. It will be apparent therefore that the springs 84 act to release the reverse clutch piston I3 and that the springs 88 act to release the low clutch piston 50.

Due to the limits imposed on their extension, the springs 84 and 88 are slightly compressed when the pistons 50 and I3 are in fully released position and this condition, in conjunction with the tying together of these pistons, insures that the springs can precisely center the pistons in neutral position. Variations in spring pressure are thereby avoided which might otherwise cause one of the pistons to stop short of true neutral position, i. e., when both pistons are released, with consequent dragging of the associated clutch plates.

The hydraulic system for controlling the actuation of the clutches 39, 5|, 64 and I4 is schematically illustrated in Fig. 9 to which reference will now be made. The working liquid for the system is provided by the lubricating oil for the transmission and is withdrawn from a sump 89, which is characteristically a convenient lower part of the transmission housing I4, by a gear pump 90 through a pipe 9I and is discharged through a pipe 92. As indicated in Fig. 1, the pump 90 is carried by the cover 30 and is driven by a gear 93 that meshes with a gear 94 keyed to the input shaft II. A pressure relief valve 95 is bridged around the pump 90 to regulate pressure in the pipe 92. The delivery end of the pipe 92 connects with a control valve 96 which, as shown in Fig. 1, may be carried by the top wall of the transmission housing I4.

Oil is also withdrawn from the sump 89 by a gear pump 91 through a pipe 98 and is discharged through a pipe 99. As also shown in Fig. 1, the pump 91 is carried by the housing I4 and is driven from the output shaft 58 by a reduced extension.

5 I thereof. A relief valve IOI may be bridged around the pump 91 to regulate pressure in the pipe 99, but this valve may be omitted if desired since the valve 95 will regulate pressure in the system. The delivery end of the pipe 99 connects with the pipe 92 adjacent the valve 96 and the pipe 99 includes a check valve I02 which permits the oil to flow from the pump 91 to the valve 96 but prevents reverse flow which would otherwise occur when the reverse clutch I4 is engaged since the pump 91 is driven from the output shaft 58. Pipes I03, I04, I05 and I06 connect the valve 98 with the low, reverse, direct and high clutches 5|, I4, 39 and 64, respectively, and a pipe I0'I provides a return connection from the valve 96 to the sump 89.

The structural details of the control valve 96, which determines actuation of the respective hydraulic clutches, are shown in Figs. 6, 7 and 8 and will now be described. This valve includes a body I08 having a pair of spaced, horizontal, supply and return passages I09 and H0, respectively, extending inwardly of the body from the left end thereof, as viewed in Fig. 6, and terminating short of the opposite end of the body. The open end of the passage I09 connects with the delivery end of the main supply pipe 92 and the similar end of the passage H0 is connected to the inlet end of the return passage I0I. Interseoting the passages I09 and H0 are vertical cylinders III, H2, H3 and H4 spaced from left to right across the body I08, the lower ends of the cylinders being closed by the bottom wall of the body and the upper ends opening into a chamber I I5 in the upper part of thebody.

Piston valves H6, H1, H8 and H9 are slidable in the cylinders IH, H2, H3 and H4 and when in the positions shown in Fig. 6 deny communication between the passage I09 and chambers I20, I2I, I752, and I23, all respectively. the latter chambers being un :onnected with each other and located in the same horizontal plane across the l'odv H8 between the passages I09 and H0. The chamber I23 communicates with the pipe I04, the chambers I2! and I22 connect with the pipes I03 and I06 through passages I24 and I25, respectively, in the body I08, and the chamber I 23 communicates with the pipe I05. The valves H6, H1. H8 and H9 are biased upwardly by springs I26, I21, I28 and I29 seated in the bot 55 toms of the cylinders III, H2, H3 and H4, the

upper ends of the springs bearing against guides I30, IEI, I32 and I33 which are connected to the valves by necks I34, I35, I36 and I3], a l reap-e:-

tively, each neck having a diameter less than that 0 of the associated cylinder. In the operation of the control valve 95, the valves H6, H1, H8 and I !9 never mask any portion of the supply passage I09 and. in the closed positions shown in Fig. 6, are located in their respective cylinders between the passage I09 and the plane which includes the passages I20, I2I, I22 and I23; likewise, the uides I30, I3I, I32 and I33 never mask any portion of the return passage H0 since they are always positioned below this passage.

0 Necks I38, I39, I40 and MI, each similar to neck I30, extend upwardly from the valve; H8, H1, H8 and H9 for connection with guide followers I42, I43, I44 and I45 which bear against plate cams I46, I41 and I48 provided on a sleeve 75 I49 extending within the chamber H5 and jourhaled in the body I66, and against one arm of a rocker I66 pivoted in the chamber III, all respectively. The other arm of the rocker I66 is positioned for actuation by the inner end of a plunger I6I slidable through the sleeve I46 and having its outer end operably related to a shift lever I62 whose lower end is pivoted between a pair of ears I66 that are connected to the sleeve I46.

The upper end of the lever I62 extends through a slotted guide I64 provided in an extension I66 of the top wall of the body I66. The guide I64 is E-shaped in plan view, as shown in Fig. 8, lies in a plane parallel to the plane which includes the axis of the sleeve I46, and comprises a straight slot I66 which is normal to the sleeve axis and parallel slots I61, I66 and I66 which extend normally from the slot I66 towards the main portion of the body I66, the slots I66 and I56 being located at the ends of the slot I56; respectively, and the slot I51 intermediate therebetween. The extension I55 is marked along one side of the slot as at I66, I6I, I52 and I63 to indicate neutral, low, high and reverse positions, respectively, of the shift lever I52 when power is transmitted through the converter I6. Low, high and reverse positions I6I, I62 and I63 lie opposite to the slots I51, I66 and I66 which determine low, high and reverse positions of the shift lever I62 during direct drive, all respectively. From the foregoing, it will be apparent that the lever I62 may be moved to and fro along the slot I66 to thereby rock the sleeve I46 and selectively position the cams I46, I41 and I46 with respect to their associated valves, or the lever may be moved into any of the slots I61, I56 and I56 to cause the plunger II to actuate the rocker I66 and shift the valve II6 to an open position.

The shapes and angular relation of the cams I46, I41 and I46 are illustrated in Fig. 7. The working surfaces or lands of the cams are particylindrical and have the same radius, with the cam I46 disposed in generally diametral relation to the cams I41 and I46. The land of the cam I41 is longer than that of and overlaps the land of the cam I48 and the trailing end of the land of the cam I41, considered with respect to its movement in a. valve-opening direction which is clockwise in Fig. 7, is aligned with the corresponding end of the land of the cam I46. Hence, in one position of the sleeve I46, the cam I41 may open its valve II1 without either of the valves H6 and II6 being opened; in another position, the cam I41 maintains opening of the valve H1 and simultaneously the cam opens the valve II6 without the valve II6 being disturbed; and in another position, the cam I46 opens the valve II6 while the valves H1 and H6 are closed by their respective springs since the cams for the latter valves are in non-actuating positions. The ends of the land of the cam I46 connect by diverging chordal surfaces I64 with an annular bead I66 on the surface of the sleeve I46 and chordal surfaces I66 and I61 connect the ends of the lands of the cams I41 and I46 with annular beads I66 and I66 on the surface of the sleeve I46, all respectively. when the valves H6, H1 and H6 are closed, as shown in Fig. 6, the angular status of the sleeve I46 is such that the several cams are in the positions shown in Fig. '7 with the followers I42, 143 and I44 bearing against the beads I66, I66 and I56, respectively, which have the same diameter.

The details of the connections from the control valve 66 to the several clutches are illustrated in Figs. 1 and 2 to which reference will now be made. For the low clutch 6|, the delivery end of the pipe I66 connects with a passage I16 in the housing wall 21 which in turn communicates with a radial passage "I provided in a packing ring I12 that encircles the sleeve I6 adjacent the bearing 26. The inner end of the passage I1I connects with an annular channel I13 in the ring I12 which is in constant communication with a radial passage I14 in the sleeve I6 and the inner end of the latter passage connects with an annular passage I16 created by the already referred to spacing of the shaft II and the bore of the sleeve I6. The ends of the passage I16 are determined by a packing ring I16 carried by the shaft II and located just to the left of the passage I14 (see Fig. 1) and a packing ring I11 also carried by the shaft II and positioned in the plane of the pinion 26, or intermediate the low and reverse clutches 5i and 14, respectively. The annular passage I15 is in constant communication with a radial passage I16 in the sleeve I6 and the latter passage constantly connects with an annular channel I16 forming part of a radial passage I86 in a spacer ring I6I positioned between the sleeve I6 and the hub of the pinion 26. The inner end of the passage I66 merges into an annular channel I62 which constantly communicates with a passage I63 in the hub of the pinion 26 which connects with the low clutch cylinder 49.

For the high clutch 64, the delivery end of the pipe I66 connects with a radial passage I64 (see Fig. l) in a holder ring I65 that is concentric with the output shaft 68 and is bolted to the housing wall 21. Interposed between the ring I65 and shaft 56 is a packing ring I66 having peripherally thereof an annular channel I61 which constantly registers with the inner end of the passage I64 and connects by way of an included longitudinal passage I66 with a passage I66 in the hub of the gear 61 which communicates with the high clutch cylinder 66.

For the reverse clutch 14, the delivery end of the pipe I64 connects with a radial passage I66 provided in a flanged portion I6I of the cover 66 that encircles the input shaft II. The inner end of the passage I66 constantly communicates with an annular channel I62 provided in the hub of the disk 33 and inwardly of this hub, the channel I62 connects by way of an included, radial passage I66 with a registering radial passage I64 formed in the input shaft II. The inner end of the passage I64 connects with a passage I65 that ex- I tends axially of the shaft II from the outer end thereof where it is closed by a plug I66 to a point to the right of the packing ring I11 (see Fig. 2). This inner end of the passage I65 connects through a radial passage I61 in the shaft I I with an annular passage I66 established by the spacin of the sleeve from the shaft II. The left end of the passage I66 is determined by the packing ring I11 and the right end by a packing ring I66 also carried by the shaft I I. A radial passage 266 in the sleeve I6 provides constant communication between the annular channel 26I provided in a spacer ring 262 interposed between the sleeve I 6 and the hub of the pinion 26. An outer, annular channel 263 in the spacer ring 262 that is connected to the inner channel 26I by a radial passage 264 constantlycommunicates with a passage 265 in the hub of the pinion 26 that leads to the reverse clutch cylinder 12.

For the direct clutch 36 (see Fig. 2). the delivery end of the pipe I66 connects with a radial passage 206 in the annular flange I 9I which communicates by way of, as it appears in Fig. 2, an inverted, generally U-shaped passage 201 in the disk 33 with the direct clutch cylinder 31. g

In describing the operation of the transmission, it will be assumed first that the shift lever I 52 is in neutral position I60 and that the engine is idling, thus driving the input shaft I I. Under these conditions, the cams I46, I41 and I48 occupy the positions shown in Fig. '7, the associated valves I I6, I I1 and I I 8, respectively, are closed as shown in Fig. 6, and the valve I I9 is also closed since the rocker I50 is in the position also shown in Fig. 6. Hence, although the pump 90 is driven by the shaft II, the closed positions of the several valves prevents application of pressure to the clutches 39, I, 64 and 14 which are thus disengaged as shown in Fig. 2 and their respective supply pipes I05, I03, I06 and I04 are then in communication with the pipe I01 leading to the sump (see Fig. 6). Actuating liquid that may previously have engaged any of the clutches has been discharged to the sump by the action of the release spring for the clutch in question. Pressure developed by the pump 90 will be relieved by the'valve 95 and the pump 91 will not be operating since it is driven from the output shaft 58 which is at rest. Whatever drag torque may be transmitted to the sleeve I9 through the converter I6 does not produce a drive of the output shaft 53 since converter drive of this shaft can only be effected through the low, high or reverse clutches which are disengaged.

In connecting the engine to the load, advantage is ordinarily taken of the high starting torque and capacity for rapid, smooth acceleration afforded by the converter in conjunction with the facility provided by this transmission of establishing definite speeds for the output shaft for any given engine speed. Assuming that the load is to be started in low gear through the converter, the shift lever I 52 is moved fromneutral position I60 to low gear position I6I, thus rotating the sleeve I49 in a clockwise direction, as viewed in Fig. '7, until the land of the cam I41 engages the follower I43 and shifts the valve I I1 downwardly to connect the passage I09 with the chamber I2I and to mask connection between the chamber I2I and the return passage H0. The valves II 6 and H8 remain undisturbed during the above rotation of the sleeve since their followers !42 and I44 merely bear against other portions of the beads I65 and I69, and the valve H9 is also undisturbed since the shift lever I52 has not actuated the rocker I50.

The pressure of the pump 90 which has thus been established in the chamber I 2I becomes effective in the passage I24, pipe I 03 and the connecting passages and channels referred to above (see Fig. 2) leading to the low clutch cylinder 49. The low clutch 5I is thus engaged and transmits drive through the overrunning clutch 54, pinion 55 and gear 51 to the output shaft 58.

When the load is accelerated to the desired speed, the output shaft may be connected for high speed drive through the converter by engaging the high speed clutch 64. This result is accomplished by shifting the lever I 52 from its low position I6I to the high position I62, thus further rotating the sleeve in a clockwise direction, as viewed in Fig. 7, until the land of the cam I48 engages the follower I44 and moves the valve I I8 downwardly to connect the supply passage I09 with the chamber I22 and to deny communication between this chamber and the return pas- 10 sage II 0. Under these conditions, it will be noted that, due to the working length of the cam I41 and its angular relation to the cam I48, the valve II1 controlling the application of pressure to the low clutch 5I remains open so that this clutch maintains its engagement.

Pump pressure being established in the chamber I22, it becomes effective through the passage I 25, pipe I 06 .and the connecting passages and. channels (see Figs. 1 and 2) leading to the high clutch cylinder 66. The high clutch 64 is thus engaged and the power, which is applied thereto through the pinion 29 and the gear 6|, is transmitted by the clutch 64 through the gear 51 to the output shaft 58. Since the low clutch 5I remains engaged during engagement of the high clutch 64, the engine is never disconnected from the load and therefore the change from low to high speed is accomplished with a full power shift. The overrunning clutch 54 enables the high clutch 64,

.when engaged, to take command over the low clutch 5I, also engaged, since the clutch 54 during high speed operation will rotate freely without transmitting power.

If it is desired to shift from high to low speed, the lever I52 is returned to the low position I6I, thus rotating the sleeve I49 counterclockwise, as viewed in Fig. 7, until the land of the cam I48 is freed from the follower I44, but the cam I41 still bears against the follower I43 to thereby continue application of pressure to the low clutch 5 I. The valve I I8 is returned to the closed position shown in Fig. 6 by the spring I28, denying application of pump pressure to the chamber I22 and hence to the high clutch cylinder 66 and connecting this cylinder through the chamber I22 with the return passage I I0 leading to the sump 89. The release springs 69 thereupon return the piston 61 to the release position shown in Fig. 2 and the high clutch 64 is disengaged, whereupon the speed of the sleeve I9 increases until the overrunning clutch 54 again engages and power is again transmitted through the low clutch 5|. This change from high to low speed is also accomplished with a full power shift.

In each of the forward speed drives above described, power flow is through the converter I6 and the reaction member 20 thereof is held from rotating in a reverse direction to provide the required changes in flow direction of the working liquid by the overrunning clutch 24. The transat the beginning of this shift, is in high position I62 (seeFig. 8) and, as already described, the drive is through the converter I6 and the high clutch64, the low clutch 5| also being engaged but not transmitting power. Moving the lever I52 from the high converter Iposition I62 into the slot I58 determines high direct drive through the transmission in the following manner. Since this movement of the lever I52 does not change the rotational position of the sleeve I49 from that which it occupies during high speed, converter drive, the valves I I1 and I I8 remain open and the low and high clutches 5I and 64, respectively, maintain engagement. However, the indicated movement of the lever I52 does shift the plunger I 5i which rotates the rocker I50 to thereby move the follower I 45 downwardly (see Fig. 6) until the valve II9 opens to connect the supply passage I09 and the chamber I23 and to deny compump and turbines.

munciation between this chamber and the return passage H0.

Pump pressure is accordingly established in the chamber I 23, pipe I 05, and the connecting passages and channels (see Fig. 2) leading to the direct clutch cylinder 31. Therefore, the direct clutch 39 is engaged and the input shaft II is coupled directly to the sleeve I9 which transmits the drive to the output shaft 58 through the high clutch 64 in the manner described above for converter drive. Prior to shifting to high direct drive, the speed of the sleeve I9 is slightly less than engine speed due to the usual loss through the converter I6, but after shifting to direct drive, the speed of the sleeve I 9 is equalized with that of the engine.

Hence, in direct drive, the converter pump I5 and turbines I I and I6 rotate at the same or engine speed. Since there will not be any reaction against the blades of the reaction member 20, this member, as it is released by the overrunning clutch 24, will begin to rotate with the converter In view of the fact that power is not then being transmitted through the converter and all parts thereof are rotating at substantially the same speed, the power loss in the converter circuit is negligible. In reality, the rotational speed of the reaction member 20 is slightly less than that of the pump and turbines due to the drag of the bearings and the overrunning clutch 24, but the difference is small.

If the load becomes too heavy to be carried in high speed, direct drive, the lever I52 is returned to high speed, converter drive position I62, thus enabling the valve I I 9 to be shifted by the spring I29 to the closed position shown in Fig. 6. The valves II! and H8 remain open since the rotational position of the sleeve I49 is not disturbed. Pump pressure being cut off from the high clutch cylinder 31 and the latter being connected to the sump through the return passage III], the high clutch piston 38 is moved to release position by the springs 43 and the high clutch 39 is disengaged. Since the converter pump and turbines are then rotating at engine speed, the converter I6 picks up the load immediately with the reaction member 29 held against rotation by the overrunning clutch 24.

In the change from high speed, converter drive to high speed, direct drive and also in the change in the opposite direction, the engine is always connected to the load and the same condition holds true for a change from low speed, converter drive to low speed, direct drive and vice versa. In a shift from low speed, converter drive to low speed, direct drive, the lever I52 is initially in low position IBI which, as already noted, conditions the sleeve I 49 so that only the valve H1 is open and the low clutch 5I is engaged. Shifting the lever into the slot I51 does not disturb this rotational position of the sleeve I49, but does open the valve I I 9 in the manner described above to engage the direct clutch 39 which then establishes direct drive as indicated. Hence, the change from hydraulic to direct drive, and from direct to hydraulic drive in either low or high, forward speed is accomplished with a full power shift.

It is also possible to shift from low direct to high direct, or vice versa, with a full power shift, despite the fact that between these positions, the drive is temporarily through the converter I 6.

To reverse the converter drive, the lever I52 is moved to reverse position I69 (see Fig. 8) which rotates the sleeve I49 counterclockwise as viewed in Fig. '7 and opens the valve II6 by means of the cam I46, the valves III, III and H9 being closed by their respective springs. The valve II6 then permits communication between the supply passage I09 and the chamber I20,'and denies communication between this chamber and the return passage I I0. Pump pressure then becomes effective through the pipe IM and the connected channels and passages (see Fig. 2) leading to the reverse clutch cylinder I2. The piston I3 thereupon engages the clutch I4 and reverse drive is transmitted to the output shaft 58 through gears 18,,19 and 80 (see Fig. 4).

Changing from reverse converter drive to re verse direct drive merely requires that the lever I52 be moved into slot .I59 (see Fig. 8) which opens the valve II9 to effect an engagement of the direct clutch 39 without disturbing the engagement of the reverse clutch 14. The power then transmitted to the sleeve I9 by the direct clutch is applied through the pinion 29 to the reverse clutch I4.

When the lever I52 is moved from either of the reverse positions to neutral or any of the forward speed positions,'the valve H6 is returned to the closed position shown in Fig. 6 by the spring I26 and the reverse clutch piston 13 is shifted to the release position shown in Fig. 2 by the springs 84, the oil in the cylinder 12 being discharged to the passage H9 and thence to the sump B9.

Changing from reverse converter to reverse direct drive and vice versa is characterized by a full power shift, but not in changing-from any of the forward speeds to reverse and in the opposite direction since 'a full power shift is not desirable under these conditions.

While having general application, this transmission is more specifically intended for use in crawler tractors and trucks. The provision of the change speed mechanism enables the operator in either hydraulic or direct drive to select speed ratios that fit the workat hand and to effect these selections in all forward speeds, whether hydraulic or direct, with a full power shift, plus a like capacity in selecting hydraulic or direct drive in reverse speed. The transmission is compactly arranged, particularly as regards the use of a driving or input sleeve which surrounds the input shaft, is common to the converter and direct drive elements of the transmission, and is selectively connectible to the change speed devices.

We claim:

1. In a power transmission, the combination of an input shaft, a sleeve surrounding the input shaft, a hydraulic torque converter including a pump member connected to the input shaft, a turbine member and a reaction member, the turbine member being connected to one part of the sleeve and an overrunning clutch being interposed between the reaction member and a fixed part of the transmission, an output shaft, means connectible to the sleeve and output shaft comprising a low speed gear train including an overrunning clutch, a high speed gear train, and friction clutches for controlling power flow through the gear trains, respectively, a friction clutch for directly connecting another part of the sleeve to the input shaft, means for selectively controlling power flow through theconverter or directly to the sleeve by disengaging and engaging the direct clutch, respectively, and means operable during converter and direct drive for selectively controlling the low speed clutch and for controlling 13 the high speed clutch conjointly with the actuation of the low speed clutch.

2. In a power transmission, the combination of an input shaft, a sleeve Surrounding the input shaft, a hydraulic torque converter including a pump member connected to the input shaft, a turbine member and a reaction member, the turbine member being connected to one part of the sleeve and an overrunning clutch being interposed between the reaction member and a fixed part of the transmision, an output shaft, means connectible to the sleeve and output shaft comprising a low speed gear train including an overrunning clutch, a high speed gear train, and hydraulically actuated friction clutches for controlling power flow through the gear trains, respectively, a hydraulically actuated friction clutch for directly connecting another part of the sleeve to the input shaft, and a hydraulic pressure system including all said clutches and a control valve, the valve being operable to selectively control power flow through the converter or directly to the sleeve by disengaging and engaging the direct clutch, respectively, and for converter and direct drives to selectively control the low speed clutch and the high speed clutch conjointly with the actuation of the low speed clutch. V

3. In a power transmission, the combination of an input shaft, a sleeve surrounding the input shaft, a hydraulic torque converter including a pump member connected to the input shaft, a turbine member and a reaction member, the turbine member being connected to one end of the sleeve and an overrunning clutch being interposed between the reaction member and a fixed part of the transmission, an output shaft, means connectible to an intermediate portion of the sleeve and output shaft comprising a low speed gear train including an overrunning clutch, a high speed gear train, and hydraulically actuated friction clutches for controlling power flow through the gear trains, respectively. a hydraulically actuated friction clutch for directly connecting the other end of the sleeve to the input shaft, and a hydraulic pressure system including all said clutches and a control valve, the valve being operable to selectively control power flow through the converter or directly to the sleeve by disengaging and engaging the direct clutch, respectively, and for converter and direct drives to selectively control the low speed clutch and the high speed clutch conjointly with the actuation of the low speed clutch.

4. In a power transmission, the combination of an input shaft, a sleeve surrounding the input shaft, a hydraulic torque converter including a pump member connected to the input shaft, a turbine member and a reaction member, the turbine member being connected to one end of the sleeve and an overrunning clutch being interposed between the reaction member and a fixed part of the transmission, an output shaft, means connectible to an intermediate portion of the sleeve and the output shaft comprising a low speed gear train including an overrunning clutch, a high speed gear train, a reverse speed gear train and hydraulically actuated friction clutches for controlling power flow through the gear trains, respectively, a hydraulically actuated friction clutch for directly connecting the other end of the sleeve to the input shaft, and a hydraulic pressure system including all said clutches and a control valve, the valve being operable to and engaging the direct clutch, respectively, and for converter and direct drives to selectively control the low speed clutch, the high speed clutch conjointly with the actuation of the low speed clutch, and the reverse clutch.

5. In a power transmission, the combination of an input shaft, a sleeve surrounding the input shaft, a hydraulic torque converter including a pump member connected to the input shaft, a turbine member and a reaction member, the turbine member being connected to one end of the sleeve and an overrunning clutch being interposed between the reaction member and a fixed part of the transmission, an output shaft, a carrier pinion splined to an intermediate portion of the sleeve, a high speed gear journaled on the output shaft in constant mesh with the carrier pinion, a low speed, hydraulically actuated friction clutch carried by one side of the carrier pinion, means driven by the low speed clutch comprising a second sleeve journaled on the first sleeve and internally splined for engagement with selected plates of the low speed clutch, a first gear journaled on the second sleeve, an overrunning clutch interposed between the second sleeve and first gear, and a second gear in constant mesh with the first gear and keyed to the output shaft, the first and second gears constituting a low speed gear train, a high speed, hydraulically actuated friction clutch carried by the second gear with the plates thereof alternately connected to the second gear and high speed gear, the carrier pinion, high speed and second gears constituting a high speed gear train, a reverse speed, hydraulically actuated friction clutch mounted on the other side of the carrier pinion, a reverse speed gear train driven by the reverse clutch comprising a pinion journaled on the first sleeve, a gear keyed to the output shaft and an idler gear meshing with the last named pinion and gear, a hydraulically actuated friction clutch for directly connecting the other end of the sleeve to the input shaft, and a hydraulic pressure system including all said clutches and a control valve, the valve being operable to selectively control power flow through the converter or directly to the sleeve ,by disengaging and engaging the direct clutch, respectively, and for converter and direct drives to selectively control the low speed clutch, the high speed clutch conjointly with the actuation of the low speed clutch, and the reverse clutch.

6. In a power transmission, the combination of an input shaft, a sleeve surrounding the input shaft, a hydraulic torque converter including a pump member connected to the input shaft and a turbine member connected to one part of the sleeve, an output shaft, means connectible to the sleeve and output shaft comprising a low speed gear train including an overrunning clutch, a high speed gear train, and friction clutches for controlling power flow through the gear trains,

respectively, and means for selectively controlling the low speed clutch and for controlling the high speed clutch conjointly with the actuation of the low speed clutch.

7. In a power transmission, the combination of an input shaft, a sleeve surrounding the input shaft, a hydraulic torque converter including a pump member connected to the input shaft and a turbine member connected to the sleeve, an output shaft, means connectible to the sleeve and output shaft comprising a low speed gear train including an overrunning clutch, a high speed gear train, hydraulically actuated clutches for controlling power flow through the gear trains, respectively, and a hydraulic pressure system including all said clutches and a control valve, the valve being operable to selectively control the low speed clutch and the high speed clutch conjointly with the actuation of the low speed clutch.

8. In a power transmission, the combination of an input shaft, a sleeve surrounding the input shaft, a hydraulic torque converter including a pump member connected to the input shaft, a turbine member and a reaction member, the turbine member being connected to one end of the sleeve and an overrunning clutch being interposed between the reaction member and a fixed part of the transmission, an output shaft, a carrier pinion splined to an intermediate portion of the sleeve, a high speed gear iournaled on the output shaft in constant mesh with the carrier pinion, a low speed, hydraulically actuated, friction clutch carried by one side of the carrier pinion, means driven by the low speed clutch comprising a second sleeve journaled on the first sleeve, a first gear journaled on the second sleeve, an overrunning clutch interposed between the second sleeve and first gear, and a second gear in constant mesh with the first gear and keyed to the output shaft, the first and second gears constituting a low speed gear train, a high speed, hydraulically actuated, friction clutch carried by the second gear with the plates thereof alternately connected to the second gear and high speed gear, the carrier pinion, high speed and second gears constituting a high speed gear train, a hydraulically actuated friction clutch for directly connecting the other end of the sleeve to the input shaft, and a hydraulic pressure system including all said clutches and a control valve, the valve being Operable to selectively control power flow through the converter or directly to the sleeve by disengaging and engaging the direct clutch, respectively, and for converter and direct drives to selectively control the low speed clutch and the high speed clutch conjointly with the actuation of the low speed clutch.

9. In a power transmission, the combination of an input shaft, an output shaft, a member intermediate the shafts with respect to the direction of power flow, a hydraulic torque converter including a pump member connected to the input shaft, a turbine member and a reaction member, the turbine member being connected to one part of the intermediate member and an overrunning clutch being interposed between the reaction member and a fixed part of the transmission, means connectible to the intermediate member and output shaft comprising a low speed gear train including an overrunning clutch, a high speed gear train, and friction clutches for controlling power flow through the gear trains, respectively, a friction clutch for directly connecting another part of the intermediate member to the input shaft, means for selectively controlling power flow through the converter or directly to the sleeve by disengaging and engaging the direct clutch, respectively, and meansoperable during converter and direct drive for selectively controlling the low speed clutch and for controlling the high speed clutch conjointly with the actuation of the low speed clutch.

10. In a power transmission, the combination of an input shaft, an output shaft, a member intermediate the shafts with respect to the direction of power flow, a hydraulic torque converter including a pump member connected to the input shaft and a turbine member connected to the intermediate member, means connectible to the intermediate member and output shaft comprising a low speed gear train including an overrunning clutch, a high speed gear train, and friction clutches for controlling power flow through the gear trains, respectively, and means for selectively controlling the low speed clutch and for controlling the high speed clutch conjointly with the actuation of the low speed clutch.

JAMES B. BLACK. WILBUR F. SHURTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

